United States Department of Justice moved to block the proposed ATT – tmobile usa merger, by filing a antitrust suit. If completed the sale would have ensured there was only one GSM carrier left in us and virtually monopoly in GSM space and Duopoly in the mobile market (along with verizon cdma operator).
With already lower number of operators in the country, any move to further consolidate mobile space would lead to higher prices and poor quality of Service. Currently ATT is No 2 operator behind Verizon and t-mobile is No 4 behind sprint.
Many MNVO s (mobile virtual network operator) along with Sprint had raised their concerns on the impact the Sale would have on them. ATT could have potentially killed MNVO's with its new position and Sprint couldn't have effectively competed against bigger rivals in ATT and Verizon.
fcc Chairman Julius Genachowski also commented that the Merger does raise several questions and shared similar views to that of DOJ.